Lab Reports

Cellulosic Ethanol Breakthrough

Lee Lynd, Thayer’s Paul E. and Joan H. Queneau Distinguished Professor in Environmental Engineering Design, and his team have engineered a cellulose-dissolving bacterium that could lead to cheaper and more sustainable ethanol production. In this country, fuel ethanol is produced from corn. Producing ethanol from cellulosic feedstocks — such as wood, grass, and various residues — rather than food sources has obvious advantages. But a key constraint to the feasibility of ethanol production from cellulose is the cost of cellulase, the enzymes that convert fibrous biomass into sugars that can be fermented.

Currently, ethanol production also utilizes yeast, which grows at moderate temperatures of 30 to 35 degrees C. In a major breakthrough, Lynd’s team has engineered a new bacterium, strain ALK2, that grows at 50 to 60 degrees C. — a temperature that speeds the breakdown of cellulose — and ferments all sugars in the biomass into ethanol. Under controlled conditions, Lynd reports, the amount of cellulase needed to break down cellulosic feedstocks is slashed in half when ALK2 is used in place of yeast.

“This work shows that a new class of potentially important organisms can be engineered to produce ethanol as the only fermentation product,” says Lynd, who is chief scientific officer and co-founder of Mascoma Corp., a leading developer of cellulosic biofuel technology. “This opens up new and exciting possibilities going forward,” he adds, noting that Mascoma plans to test strain ALK2 in its pilot plant in Rome N.Y.

Therapy in Space

Cramped quarters. Life-or-death decisions. Missions that last months or years. These are just some of the psychological stressors astronauts face. To help them cope, Thayer adjunct professor Dr. Jay Buckey Jr., a former astronaut, has teamed with Dr. James Cartreine of Harvard Medical School and other researchers with the National Space Biomedical Research Institute to develop an interactive, multimedia program called the Virtual Space Station. According to Buckey, the multimedia aspect of the program, which enters clinical trials this winter, provides an important emotional component. “Just like a good movie, it will draw you in and let you respond to the characters,” he says.

While participating in NASA’s Neurolab mission on the Space Shuttle Columbia in 1998, Buckey became interested in addressing potential barriers to flights to Mars or other long-duration missions. Psychological stressors, such as interpersonal conflict or depression, can destroy missions if they are not handled well, he says. With the Virtual Space Station, on-screen psychologists lead users through lectures, exercises, interactive simulations, and programmed interventions. Astronauts can take diagnostic tests, work through simulations, and practice problem-solving strategies. The system, which runs on any laptop, will be accessible anytime, anywhere. Currently, space-based astronauts can only consult with therapists on the ground when communication links are available.

The Virtual Space Station also has practical applications here on earth. Doctors’ offices, schools, oil rigs, and other remote locations would benefit from the portable therapy. Buckey hopes the program will enable more people to receive assistance for conditions that are sometimes stigmatized. “Often people are more comfortable working with a computer for these kinds of problems,” he says. “With this program, we hope that people will seek help earlier, rather than letting the situation become worse.”

—Elizabeth Kelsey

Fighting Decompression Sickness in Space

Another space project of Buckey’s that has earth-bound applications is his work with decompression sickness (DCS). Because current spacecraft and suit designs require astronauts to move through different pressure environments, the prevention of DCS is a priority for spacewalks. When humans move from areas of high pressure to low, nitrogen can be released in the body in the form of bubbles. Buckey and Creare Inc. are currently developing a dual-frequency instrument to detect and size nitrogen bubbles in body tissue. The instrument uses two frequencies of ultrasound (similar to the frequencies clinical ultrasound machines use) to detect and size bubbles through the chest wall as they move through the heart. The instrument also can detect small, stationary bubbles in tissue — a unique capability. One potential benefit is the ability to detect the earliest stages of DCS and allow for preventative strategies like oxygen pre-breathing and the limiting physical activity at critical times. Further, the instrument can potentially be used in coronary bypass surgery to distinguish between solid and gaseous emboli and in industrial and aviation applications to determine the gas saturation in fluids.

—Elizabeth Kelsey

Power Line De-Icing

Russia and China are taking advantage of Professor Victor Petrenko’s de-icing system for power lines. Both countries have placed orders with Petrenko’s company, Ice Engineering LLC.

Petrenko’s variable resistance cable (VRC) de-icing system switches the electrical resistance of a standard power line from low to high, automatically creating heat to melt ice build-up or keep it from forming in the first place. The system can be implemented for less than a ten percent increase in overall cost and can also be installed as part of regularly scheduled maintenance. “The beauty of the VRC system is that it’s fully customizable and is an affordable addition to the current manufacturing and installation process,” says Ice Engineering vice president Gabriel Martinez.